Refrigerant compressor and cooling apparatus comprising the same

ABSTRACT

A refrigerant compressor is configured such that a compressor unit is installed in a hermetically sealed container, an HFC type refrigerant or a mixture thereof and a refrigerator oil having compatibility with the refrigerant are charged into the hermetically sealed container, and the refrigerator oil essentially comprises a polyvinyl ether type compound having structural units represented by the following general formula (1): ##STR1## wherein n is an integral number in the range of 1 or more, R1 to R3 are each a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms and may be the same or different, R4 is an alkyl group having 1 to 4 carbon atoms, and units in which R4 is an alkyl group having 1 to 2 carbon atoms are 40 to 100% and units in which R4 is an alkyl group having 3 to 4 carbon atoms are 0 to 60%. As a result, the generation of a carboxylic acid caused by thermal cracking or hydrolysis due to frictional heat generated by sliding members is prevented and the generation of sludge is thereby suppressed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a refrigerant compressor which uses1,1,1,2-tetrafluoroethane (to be referred to as R134a hereinafter) whichis an HFC type refrigerant or a mixture of HFC type refrigerants (suchas a mixture of R134a, R32 and R125, a mixture of R134a, R143a and R125or a mixture of R32 and R125) as a refrigerant and a refrigerator oilhaving compatibility with the refrigerant and to a cooling apparatus.

2. Background Art

Most refrigerant compressors for refrigerators, automatic vendingmachines and show cases have conventionally used dichlorodifluoromethane(to be referred to as R12 hereinafter) as a refrigerant. This R12 fallsunder flon regulations because of the disruption of the ozone layer.R134a is now being studied for use in refrigerators as a substitute forthis R12 (refer to Laid-open Japanese Patent Application No. Hei1-271491, for example).

Although chlorodifluoromethane (R22) has been used in air conditionersand the like, much attention is paid to HFC type mixed refrigerants froma viewpoint of environmental preservation.

However, HFC type refrigerants such as the above-described R134a havepoor compatibility with a refrigerator oil such as mineral oil oralkylbenzene oil which is currently used and cause a failure inlubricating the compressor due to the bad returning of the oil to thecompressor and the absorption of the separated refrigerant at the timeof activation.

Therefore, the inventors of the present invention have studied a polyolester type oil as a refrigerator oil which has compatibility with HFCtype refrigerants such as R134a. However, when this polyol ester typeoil is used in a rotary type compressor, a fatty acid produced by thehydrolysis of the oil caused by heat corrodes sliding members and causeswear. Powders produced by this wear exert a bad influence on organicmaterials such as magnet wires of electric elements of the compressorand thus impair the durability of the compressor.

The inventors have conducted studies to use a combination of an HFC typerefrigerant as a refrigerant and a polyol ester type oil as arefrigerator oil in a rotary type compressor and have found that acarboxylic acid which is produced by the hydrolysis of the polyol estertype oil for lubricating sliding members caused by the frictional heatof the sliding members of the rotary type compressor corrodes iron typematerials or reacts with iron type materials to become metal soap orsludge, thereby reducing refrigerating capacity.

As a result, the inventors have found that the thermal cracking of thepolyol ester type oil caused by frictional heat generated by the slidingmembers can be suppressed by a combination of a specific polyol estertype oil, a specific additive and a specific sliding material (refer toLaid-open Japanese Patent Application No. Hei 6-295357).

However, according to the above technique, it is necessary to strictlycontrol the production process, that is, the concentrations of water,chlorine and oxygen, in order to suppress hydrolysis when the polyolester type oil is used. Therefore, the above invention has a problemthat control is troublesome.

SUMMARY OF THE INVENTION

It is an object of the present invention which has been made to solvethe above problem to provide a high-performance refrigerant compressorwhich uses a polyvinyl ether type oil having compatibility with an HFCtype refrigerant such as R134a as a refrigerator oil to suppress theproduction of a carboxylic acid caused by thermal cracking or hydrolysisdue to the frictional heat of sliding members and the generation of asludge caused thereby without carrying out troublesome process control.

According to a first aspect of the present invention, there is provideda refrigerant compressor comprising a hermetically sealed container anda compressor unit installed in the hermetically sealed container,wherein an HFC type refrigerant or a mixture thereof and a refrigeratoroil having compatibility with the refrigerant are charged into thehermetically sealed container, and the refrigerator oil essentiallycomprises a polyvinyl ether type compound having structural unitsrepresented by the following general formula (1): ##STR2## wherein n isan integral number in the range of 1 or more, R1 to R3 are each ahydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms and maybe the same or different, R4 is an alkyl group having 1 to 4 carbonatoms, and units in which R4 is an alkyl group having 1 to 2 carbonatoms are 40 to 100% and units in which R4 is an alkyl group having 3 to4 carbon atoms are 0 to 60%.

According to a second aspect of the present invention, there is provideda refrigerant compressor in which the refrigerant is selected from thegroup consisting of 1,1,1,2-tetrafluoroethane (R134a), an azeotropicmixed refrigerant consisting of 50 wt % of difluoromethane (R32) and 50wt % of pentafluoroethane (R125), and a pseudo-azeotropic mixedrefrigerant consisting of 44 wt % of pentafluoroethane (R125), 52 wt %of trifluoroethane (R143a) and 4 wt % of 1,1,1,2-tetrafluoroethane(R134a).

According to a third aspect of the present invention, there is provideda refrigerant compressor in which the refrigerator oil comprises 0.01 to1.0 wt % of a phenolic antioxidant as an essential component and 0.01 to2 wt % of an epoxy type or carbodiimide type compound.

According to a fourth aspect of the present invention, there is provideda refrigerant compressor in which the refrigerator oil comprises 0.1 to2 wt % of a phosphoric ester type compound.

According to a fifth aspect of the present invention, there is provideda refrigerant compressor in which the compressor unit comprises a vanemade from an iron type material or a carbon composite materialinfiltrated with aluminum and a roller made from an iron type material.

According to a sixth aspect of the present invention, there is provideda refrigerant compressor in which the compressor unit comprises a vanemade from an iron type material such as high speed tool steel or an SUStype material subjected to a single or composite surface treatment byion nitridation, nitrosulphurization or CrN.

According to a seventh aspect of the present invention, there isprovided a refrigerant compressor in which the units in which R4 is analkyl group having 1 to 2 carbon atoms are 80 to 100% and the units inwhich R4 is an alkyl group having 3 to 4 carbon atoms are 0 to 20%.

According to an eighth aspect of the present inventing, there isprovided a refrigerant compressor in which the refrigerant comprises atleast two compositions selected from the group consisting of fluorinatedhydrocarbons represented by the following general formula (2):

    C.sub.l H.sub.m F.sub.n                                    ( 2)

(wherein when l=1, m=1˜2, n=2˜3 and m+n=4, when l=2, m=1˜4, n=2˜5 andm+n=6, and when l=3, m 1˜3, n=5˜7 and m+n=8).

According to a ninth aspect of the present invention, there is provideda refrigerant compressor in which the refrigerant is selected from thegroup consisting of an azeotropic mixed refrigerant consisting of 50 wt% of difluoromethane (R32) and 50 wt % of pentafluoroethane (R125) and apseudo-azeotropic mixed refrigerant consisting of 44 wt % ofpentafluoroethane (R125), 52 wt % of trifluoroethane (R143a) and 4 wt %of 1,1,1,2-tetrafluoroethane (R134a).

According to a tenth aspect of the present invention, there is provideda refrigerant compressor in which the refrigerator oil comprises 0.01 to1.0 wt % of a phenolic antioxidant as an essential component and 0.01 to2 wt % of an epoxy type or carbodiimide type compound.

According to an eleventh aspect of the present invention, there isprovided a refrigerant compressor in which the refrigerator oilcomprises 0.1 to 2 wt % of a phosphoric ester type compound.

According to a twelfth aspect of the present invention, there isprovided a refrigerant compressor in which the compressor unit comprisesa vane made from an iron type material or a carbon composite materialinfiltrated with aluminum and a roller made from an iron type material.

According to a thirteenth aspect of the present invention, there isprovided a refrigerant compressor in which the compressor unit comprisesa vane made from an iron type material such as high speed tool steel oran SUS type material subjected to a single or composite surfacetreatment by ion nitridation, nitrosulphurization or CrN.

According to a fourteenth aspect of the present invention, there isprovided a refrigerant compressor in which the units in which R4 is analkyl group having 1 to 2 carbon atoms are 60 to 100% and the units inwhich R4 is an alkyl group having 3 to 4 carbon atoms are 0 to 40%.

According to a fifteenth aspect of the present invention, there isprovided a refrigerant compressor in which the refrigerant comprises atleast two compositions selected from the group consisting of fluorinatedhydrocarbons represented by the following general formula (2):

    C.sub.l H.sub.m F.sub.n                                    ( 2)

(wherein when l=1, m=1˜2, n=2˜3 and m+n=4, when l=2, m=1˜4, n=2˜5 andm+n=6, and when l=3, m=1˜3, n=5˜7 and m+n=8).

According to a sixteenth aspect of the present invention, there isprovided a refrigerant compressor in which the refrigerant is apseudo-azeotropic mixed refrigerant consisting of 23 wt % ofdifluoromethane (R32), 25 wt % of pentafluoroethane (R125) and 52 wt %of 1,1,1,2-tetrafluoroethane (R134a).

According to a seventeenth aspect of the present invention, there isprovided a refrigerant compressor in which the refrigerator oilcomprises 0.01 to 1.0 wt % of a phenolic antioxidant as an essentialcomponent and 0.01 to 2 wt % of an epoxy type or carbodiimide typecompound.

According to an eighteenth aspect of the present invention, there isprovided a refrigerant compressor in which the refrigerator oilcomprises 0.1 to 2 wt % of a phosphoric ester type compound.

According to a nineteenth aspect of the present invention, there isprovided a refrigerant compressor in which the compressor unit comprisesa vane made from an iron type material or a carbon composite materialinfiltrated with aluminum and a roller made from an iron type material.

According to a twentieth aspect of the present invention, there isprovided a refrigerant compressor in which the compressor unit comprisesa vane made from an iron type material such as high speed tool steel oran SUS type material subjected to a single or composite surfacetreatment by ion nitridation, nitrosulphurization or CrN.

According to a twenty-first aspect of the present invention, there isprovided a cooling apparatus comprising a refrigerant compressorcomprising a hermetically sealed container and a compressor unitinstalled in the hermetically sealed container, a condenser, anexpansion device and an evaporator, which are connected by pipes,wherein an HFC type refrigerant or a mixture thereof and a refrigeratoroil having compatibility with the refrigerant are charged into thehermetically sealed container, and the refrigerator oil essentiallycomprises a polyvinyl ether type compound having structural unitsrepresented by the following general formula ##STR3## wherein n is anintegral number in the range of 1 or more, R1 to R3 are each a hydrogenatom or a hydrocarbon group having 1 to 8 carbon atoms and may be thesame or different, R4 is an alkyl group having 1 to 4 carbon atoms, andunits in which R4 is an alkyl group having 1 to 2 carbon atoms are 40 to100% and units in which R4 is an alkyl group having 3 to 4 carbon atomsare 0 to 60%.

BRIEF DESCRIPTION OF THE DRAWINGS

These objects and advantages of the present invention will become clearfrom the following description with reference to the accompanyingdrawings, wherein:

FIG. 1 is a longitudinal sectional view of a rotary type compressoraccording to an embodiment of the present invention;

FIG. 2 is a transverse sectional view of a rotary type compressor of thepresent invention;

FIG. 3 is a diagram for explaining an Amsler wear tester;

FIG. 4 is a diagram for explaining a bench-stand tester; and

FIG. 5 is a refrigerant circuit diagram of a cooling apparatus accordingto the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is described hereinafter with reference toembodiments shown in the accompanying drawings.

FIG. 1 is a longitudinal sectional view of a rotary type compressor.FIG. 2 is a sectional view cut on line A--A of the rotary typecompressor of FIG. 1. In FIGS. 1 and 2, reference numeral 1 denotes ahermetically sealed container in which an electric element 2 and arotary compression element 3 driven by this electric element as acompressor unit are installed in the container in such a manner that theelectric element 2 is positioned above the rotary compression element 3.The electric element 2 comprises a stator 5 having a coil 4 insulated byan organic material and a rotor 6 arranged inside the stator. The rotarycompression element 3 comprises a cylinder 7, a roller 10 which isturned along the interior wall of the cylinder 7 by an eccentric portion9 of a rotary shaft 8, a vane 12 pressed by a spring 11 for partitioningthe inside of the cylinder 7 into a suction side and a discharge sidewhen it is pressure contacted to the peripheral surface of the roller,and an upper bearing 13 and a lower bearing 14 for supporting the rotaryshaft 8 and closing the openings of the cylinder 7.

A discharge port 15 communicating with the discharge side of thecylinder 7 is formed in the upper bearing 13. A discharge valve 16 foropening and closing the discharge port 15 and an exhaust muffler 17 forcovering the discharge valve are attached to the upper bearing 13.

The roller 10 is formed from an iron type material such as cast iron aswill be described hereinafter, the vane 12 is formed from an iron typematerial, a composite material of aluminum and carbon, or an iron typematerial such as high speed tool steel or an SUS type material subjectedto a single or composite surface treatment by ion nitridation,nitrosulphurization, CrN or the like.

An HFC type refrigerant or a mixture thereof is charged into a bottomportion of the hermetically sealed container 1. The refrigerant is1,1,1,2-tetrafluoroethane (R134a) alone, an azeotropic mixed refrigerant(to be referred to as R410A hereinafter) consisting of 50 wt % ofdifluoromethane (R32) and 50 wt % of pentafluoroethane (R125), apseudo-azeotropic mixed refrigerant (to be referred to as R404Ahereinafter) consisting of 44 wt % of pentafluoroetane (R125), 52 wt %of trifluoroethane (R143a) and 4 wt % of 1,1,1,2-tetrafluoroethane(R134a), or a pseudo-azeotropic mixed refrigerant (to be referred to asR407C hereinafter) consisting of 23 wt % of difluoromethane (R32), 25 wt% of pentafluoroethane (R125) and 52 wt % of 1,1,1,2-tetrafluoroethane(R134a).

Oil used as the refrigerator oil has compatibility with the aboverefrigerant.

Stated more specifically, the refrigerator oil essentially comprises apolyvinyl ether type compound having structural units represented by thefollowing general formula ##STR4## wherein n is an integral number inthe range of 1 or more, R1 to R3 are each a hydrogen atom or ahydrocarbon group having 1 to 8 carbon atoms and may be the same ordifferent, R4 is an alkyl group having 1 to 4 carbon atoms, and units inwhich R4 is an alkyl group having 1 to 2 carbon atoms are 40 to 100% andunits in which R4 is an alkyl group having 3 to 4 carbon atoms are 0 to60%. Or the refrigerator oil essentially comprises a polyvinyl ethertype compound having structural units represented by the above generalformula (1), in which the units in which R4 is an alkyl group having 1to 2 carbon atoms are 40 to 100% and the units in which R4 is an alkylgroup having 3 to 4 carbon atoms are 0 to 60%. In addition, therefrigerator oil essentially comprises a polyvinyl ether type compoundhaving structural units represented by the above general formula (1), inwhich the units in which R4 is an alkyl group having 1 to 2 carbon atomsare 40 to 100% and the units in which R4 is an alkyl group having 3 to 4carbon atoms are 0 to 60% As an antioxidant, 0.01 to 1.0 wt % of aphenolic antioxidant (such as DBPC) is contained as an essentialcomponent and 0.01 to 2 wt % of an epoxy type or carbodiimide typecompound is contained as an acid trapping agent in the refrigerator oil.

As an extreme-pressure additive or an anti-wear agent, 0.1 to 2 wt % ofa phosphoric ester type compound such as tricresyl phosphate (TCP) iscontained in the refrigerator oil.

Glycidyl ether which is one of epoxy type compounds is selected from thegroup consisting of hexylglycidyl ether, 2-ethylhexylglycidyl ether andisooctadecylglycidyl ether.

The above carbodiimide type compounds are represented by the generalformula R5--N═C═N--R6 wherein R5 and R6 are each selected from an alkylgroup and an alkyl-substituted aromatic group.

The oil 18 lubricates a sliding surface between the roller 10 and thevane 12 which are the sliding members of the rotary compression element3.

The refrigerant which flows into the cylinder 7 of the rotarycompression element 3 and is compressed by cooperation between theroller 10 and the vane 12 is R134a, R410A, R407C or R404A havingcompatibility with the polyvinyl ether type oil 18 as described above.

Reference numeral 19 denotes a suction pipe, attached to thehermetically sealed container 1, for guiding the refrigerant to thesuction side of the cylinder 7 and 20 a discharge pipe, attached to theupper wall of the hermetically sealed container 1, for discharging therefrigerant compressed by the rotary compression element 3 to theoutside of the hermetically sealed container 1 through the electricelement 2.

In the above configured rotary compressor using the refrigerator oilcomposition, the refrigerant flowing into the suction side of thecylinder 7 from the suction pipe 19 is compressed by cooperation betweenthe roller 10 and the vane 12, passes through the discharge port 15 toopen the discharge valve 16 and is discharged into the exhaust muffler17. The refrigerant in this exhaust muffler is discharged from thedischarge pipe 20 to the outside of the hermetically sealed container 1through the electric element 2. The oil 18 is supplied to the slidingsurface between the sliding members such as the roller 10 and the vane12 of the rotary compression element 3 to lubricate the surface. Therefrigerant compressed in the cylinder 7 is prevented from being leakedinto a low-pressure side.

The following examples and comparative examples are given to furtherillustrate the present invention.

FIG. 3 is a diagram for explaining a wear test which has been conductedusing an Amsler wear tester.

In this respect, reference numeral 21 denotes a fixed piece equivalentto the vane and having a curved end with a radius of 4.7 mm, whichreceives a load L of 100 kg. Reference numeral 22 represents a rotatingpiece equivalent to the roller and having a diameter of 45 mm. Thisrotating piece is turned at a speed of 400 rpm for 20 hours while apressure contact portion thereof with the fixed piece 21 is suppliedwith various polyvinyl ether type oils at a rate of 120 cc/min.

Table 1 shows the results of abrasion tests made on the followingcombinations using the Amsler abrasion tester shown in FIG. 3.

                  TABLE 1    ______________________________________                        Wear Quantity of           Structure of                    Total Acid                              Test Sample    Vane     Polyvinyl  Number    Vane    Roller    Material Ether (R4) (TAN)     0.1x (mm)                                          (μm)    ______________________________________    Comparative             Type A     0.09      0.7     -3    Example    Example 1             Type A     0.01      0.6     -1    Example 2             Type A     not more  0.1     0                        than 0.01    Example 3             Type A     not more  0.1     0                        than 0.01    Example 4             Type A     not more  0.1     0                        than 0.01    ______________________________________

VANE!

Comparative Example: high speed tool steel (SKH51)

composition : C: 0.8 to 0.9, Si: not more than 0.4, Mn: not more than0.4, P: not more than 0.03, S: not more than 0.03, Cr; 3.8 to 4.5, Mo:4.5 to 5.5, W: 5.5 to 6.7, V: 1.6 to 2.2, Cu: not more than 0.25, Ni:not more than 0.25

Example 1: composite material comprising aluminum and carbon; statedspecifically, carbon composite material infiltrated with aluminum(Carbon AL)

composition: C: 55, Al: 36, Si: 6, others (such as Mg): 3 (in wt %)

Example 2: iron type material such as high speed tool steel which issubjected to a surface treatment by nitrosulphurization; statedspecifically, a material equivalent to SKH55 containing the followingcomponents and subjected to a surface treatment by plasmanitrosulphurization

composition: C: 2.14, Si: 0.32, Cr: 4.21, Mn: 0.32, W: 11.5, V: 7.0, Co:8.0, Mo: 2.53, Fe: the balance (in wt %)

Example 3: SUS type material subjected to a surface treatment bynitrosulphurization; stated specifically, SUS440 type materialcontaining the following components and subjected to a surface treatmentby plasma nitrosulphurization

composition: C: 1.8 to 2.3, Si: not more than 1, Cr: 20 to 24, Mo: 0.5to 2.6, Fe: the balance (in wt %)

Example 4: iron type material such as high speed tool steel subjected toa surface treatment by ion nitridation and further a surface treatmentby CrN

ROLLER! cast iron material (to be referred to as E-3 hereinafter)

composition: T.C.(total carbon): 0.56 to 0.64, Si: 2.2 to 2.9, Mn: 0.6to 1.0, P: 0.18 max, S: 0.08 max, Ni: 0.1 to 0.2, Cr: 0.20 max, Mo: 0.07to 0.2, Ti: 0.25 max, Fe: the balance

OIL! oil essentially comprising a polyvinyl ether type compound havingstructural units represented by the following general formula (1):##STR5## wherein n is an integral number in the range of 1 or more, R1to R3 are each a hydrogen atom or a hydrocarbon group having 1 to 8carbon atoms and may be the same or different, R4 is an alkyl grouphaving 1 to 4 carbon atoms, and units in which R4 is an alkyl grouphaving 1 to 2 carbon atoms are 50% and units in which R4 is an alkylgroup having 3 to 4 carbon atoms are 50%, and further comprising 0.1 to2.0 wt % of tricresyl phosphate (TCP) and 0.01 to 10 wt % of2-ethylhexylglycidyl ether as the epoxy compound according to thepresent invention (EPOX) (to be referred to as "Type A" hereinafter).

REFRIGERANT! R134a alone

As a result, as shown in Table 1, it was confirmed that the vanematerials of Examples 1 to 3 are all superior in total acid number (TAN)and wear quantity of TP.

It is assumed that the reason for this is the thermal cracking of thepolyvinyl ether type oil caused by sliding frictional heat generated onthe sliding surface between the rotating piece 22 and the fixed piece 21was suppressed.

Table 2 shows the results of wear tests on the following combinationsusing an Amsler wear tester shown in FIG. 3.

                  TABLE 2    ______________________________________                        Wear Quantity of           Structure of                    Total Acid                              Test Sample    Vane     Polyvinyl  Number    Vane    Roller    Material Ether (R4) (TAN)     0.1x (mm)                                          (μm)    ______________________________________    Comparative             Type C     0.08      0.6     -3    Example    Example 1             Type C     0.01      0.5     -1    Example 2             Type C     not more  0.1     0                        than 0.01    Example 3             Type C     not more  0.1     0                        than 0.01    Example 4             Type C     not more  0.1     0                        than 0.01    ______________________________________

VANE!

Comparative Example: high speed tool steel (SKH)

Example 1: composite material comprising aluminum and carbon; statedspecifically, carbon composite material infiltrated with aluminum(Carbon AL) composition: C: 55, Al: 36, Si: 6, others (such as Mg): 3(in wt %)

Example 2: iron type material such as high speed tool steel subjected toa surface treatment by nitrosulphurization; stated specifically, HAP 63material (equivalent to SKH54) containing the following components andsubjected to a surface treatment by plasma nitrosulphurization

composition: C: 2.14, Si: 0.32, Cr: 4.21, Mn: 0.32, W: 11.5, V: 7.0, Co:8.0, Mo: 2.53, Fe: the balance (in wt %)

Example 3: SUS type material subjected to a surface treatment bynitrosulphurization; stated specifically, SUS440 type materialcontaining the following components and subjected to a surface treatmentby plasma nitrosulphurization

composition: C: 1.8 to 2.3, Si: not more than 1, Cr: 20 to 24, Mo: 0.5to 2.6, Fe: the balance (in wt %)

Example 4: iron type material such as high speed tool steel subjected toa surface treatment by ion nitridation and further to a surfacetreatment by CrN

ROLLER! cast iron material (to be referred to as E-3 hereinafter)

composition: T. C. (total carbon): 0.56 to 0.64, Si: 2.2 to 2.9, Mn: 0.6to 1.0, P: 0.18 max, S: 0.08 max, Ni: 0.1 to 0.2, Cr: 0.20 max, Mo: 0.07to 0.2, Ti: 0.25 max

OIL! oil essentially comprising a polyvinyl ether type compound havingstructural units represented by the following general formula (1):##STR6## wherein n is an integral number in the range of 1 or more, R1to R3 are each a hydrogen atom or a hydrocarbon group having 1 to 8carbon atoms and may be the same or different, R4 is an alkyl grouphaving 1 to 4 carbon atoms, and units in which R4 is an alkyl grouphaving 1 to 2 carbon atoms are 80% and units in which R4 is an alkylgroup having 3 to 4 carbon atoms are 20%, and further comprising 0.1 to2.0 wt % of tricresyl phosphate (TCP) and 0.01 to 10 wt % of2-ethylhexylglycidyl ether as the epoxy compound according to thepresent invention (EPOX) (to be referred to as "Type C" hereinafter)

REFRIGERANT! R410A or R404A

As a result, as shown in Table 2, it was confirmed that the vanematerials of Examples 1 to 3 are all superior in total acid number (TAN)and wear quantity of TP.

It is assumed that the reason for this is the thermal cracking of thepolyvinyl ether type oil caused by sliding frictional heat generated onthe sliding surface between the rotating piece 22 and the fixed piece 21was suppressed. It is also considered that the deterioration of the oilis caused by the suppression of a catalytic function due to theineffectiveness of iron by TCP.

Table 3 shows the results of wear tests on the following combinationsusing an Amsler wear tester shown in FIG. 3.

                  TABLE 3    ______________________________________                        Wear Quantity of           Structure of                    Total Acid                              Test Sample    Vane     Polyvinyl  Number    Vane    Roller    Material Ether (R4) (TAN)     0.1x (mm)                                          (μm)    ______________________________________    Comparative             Type B     0.07      0.5     -2    Example    Example 1             Type B     not more  0.5     0                        than 0.01    Example 2             Type B     not more  0.2     -1                        than 0.01    Example 3             Type B     not more  0.2     -1                        than 0.01    Example 4             Type B     not more  0.1     0                        than 0.01    ______________________________________

VANE!

Comparative Example: high speed tool steel (SKH)

Example 1: composite material comprising aluminum and carbon; statedspecifically, carbon composite material infiltrated with aluminum(Carbon AL) composition: C: 55, Al: 36, Si: 6, others (such as Mg): 3(in wt %)

Example 2: iron type material such as high speed tool steel subjected toa surface treatment by nitrosulphurization; stated specifically, HAP63material (equivalent to SKH54) containing the following components andsubjected to a surface treatment by plasma nitrosulphurization

composition: C: 2.14, Si: 0.32, Cr: 4.21, Mn: 0.32, W: 11.5, V: 7.0, Co:8.0, Mo: 2.53, Fe: the balance (in wt %)

Example 3: SUS type material subjected to a surface treatment bynitrosulphurization; stated specifically, SUS440 type materialcontaining the following components and subjected to a surface treatmentby plasma nitrosulphurization

composition: C: 1.8 to 2.3, Si: not more than 1, Cr: 20 to 24, Mo: 0.5to 2.6, Fe: the balance (in wt %)

Example 4: iron type material such as high speed tool steel subjected toa surface treatment by ion nitridation and further to a surfacetreatment by CrN

ROLLER! cast iron material (to be referred to as E-3 hereinafter)

composition: T. C. (total carbon): 0.56 to 0.64, Si:

2.2 to 2.9, Mn: 0.6 to 1.0, P: 0.18 max, S: 0.08 max, Ni: 0.1 to 0.2,Cr: 0.20 max, Mo: 0.07 to 0.2, Ti: 0.25 max, Fe: the balance

OIL! oil essentially comprising a polyvinyl ether type compound havingstructural units represented by the following general formula (1):##STR7## wherein n is an integral number in the range of 1 or more, R1to R3 are each a hydrogen atom or a hydrocarbon group having 1 to 8carbon atoms and may be the same or different, R4 is an alkyl grouphaving 1 to 4 carbon atoms, and units in which R4 is an alkyl grouphaving 1 to 2 carbon atoms are 70% and units in which R4 is an alkylgroup having 3 to 4 carbon atoms are 30%, and further comprising 0.1 to2.0 wt % of tricresyl phosphate (TCP) and 0.01 to 10 wt % of2-ethylhexylglycidyl ether as the epoxy compound according to thepresent invention (EPOX) (to be referred to as "Type B" hereinafter)

REFRIGERANT! R407C

As a result, as shown in Table 3, it was confirmed that the vanematerials of Examples 1 to 3 are all superior in total acid number (TAN)and wear quantity of TP.

It is assumed that the reason for this is the thermal cracking of thepolyvinyl ether type oil caused by sliding frictional heat generated onthe sliding surface between the rotating piece 22 and the fixed piece 21was suppressed. It is also considered that the deterioration of the oilis caused by the suppression of a catalytic function due to theineffectiveness of iron by TCP.

Table 4 shows the results of a durability test on an actual refrigerantcompressor comprising the following elements using a bench-stand testershown in FIG. 4 based on the evaluations of Tables 1, 2 and 3.

The bench-stand tester comprises a compressor A, condenser B, expansionvalve C and evaporator D all of which are connected by pipes and testconditions are as follows:

Pressure at High Level: 27 to 28 kg/cm².G,

Pressure at Low Level: 46 kg/cm².G,

Operation Frequency: 100 Hz,

Operation Time: 1,000 hr,

Refrigerant: R134a, R410A, R404A, R407C

Temperature of Upper Portion of Case: 95 to 100° C. Each material is asfollows:

VANE!

Comparative Example 4: high speed tool steel (SKH)

Example 1: composite material comprising aluminum and carbon; statedspecifically, carbon composite material infiltrated with aluminum(Carbon AL)

composition: C: 55, Al: 36, Si: 6, others (such as Mg): 3 (in wt %)

Example 2: iron type material such as high speed tool steel subjected toa surface treatment by nitrosulphurization; stated specifically, HAP63material (equivalent to SKH54) containing the following components andsubjected to a surface treatment by plasma nitrosulphurization

composition: C: 2.14, Si: 0.32, Cr: 4.21, Mn: 0.32, W: 11.5, V: 7.0, Co:8.0, Mo: 2.53, Fe: the balance (in wt %)

Example 3: SUS type material subjected to a surface treatment bynitrosulphurization; stated specifically, SUS440 type materialcontaining the following components and subjected to a surface treatmentby plasma nitrosulphurization

composition: C: 1.8 to 2.3, Si: not more than 1, Cr: 20 to 24, Mo: 0.5to 2.6, Fe: the balance (in wt %)

Example 4: iron type material such as high speed tool steel subjected toa surface treatment by ion nitridation and further to a surfacetreatment by CrN

ROLLER! cast iron material (to be referred to as E-3 hereinafter)

composition: T. C. (total carbon): 0.56 to 0.64, Si: 2.2 to 2.9, Mn: 0.6to 1.0, P: 0.18 max, S: 0.08 max, Ni: 0.1 to 0.2, Cr: 0.20 max, Mo: 0.07to 0.2, Ti: 0.25 max, Fe: the balance

OIL! oils of A, B and C types shown in Tables 1 to 3 As a result, asshown in Table 4, the vane materials of Examples 1 to 4 are all goodbecause they exhibit good results and higher durability than acombination of a conventional refrigerant R-22 and mineral oil(Mineral).

As shown in FIG. 5, by connecting a refrigerant compressor a, condenserb, expansion device c and evaporator d by pipes and charging theabove-mentioned HFC type refrigerant or mixture thereof (R134a, R410A,R404A or R407C) and the above-mentioned refrigerator oil (Type A, B, orC) having compatibility with the refrigerant into the hermeticallysealed container 1 of the compressor a, there can be provided a coolingapparatus (such as a refrigerator, air conditioner or show case) whichcan prevent the returning of the oil and has a high refrigeratingcapacity.

                  TABLE 4    ______________________________________              Structure              of    Vane      Polyvinyl                       Refrigerant                                  Durability Test    Material  Ether (R4)                       Used       Wear Sludge                                             TAN    ______________________________________    Comparative              Type A   R134a      G    B     B    Example    Example 1 Type A   R134a      G    G     G    Example 2 Type A   R134a      E    E     G    Example 3 Type A   R134a      E    E     G    Example 4 Type A   R134a      E    E     G    Comparative              Type C   R410A, R404A                                  G    B     B    Example    Example 1 Type C   R410A, R404A                                  G    G     G    Example 2 Type C   R410A, R404A                                  E    E     G    Example 3 Type C   R410A, R404A                                  E    E     G    Example 4 Type C   R410A, R404A                                  E    E     G    Comparative              Type B   R407C      G    B     B    Example    Example 1 Type B   R407C      G    G     G    Example 2 Type B   R407C      E    E     G    Example 3 Type B   R407C      E    E     G    Example 4 Type B   R407C      E    E     G    ______________________________________     *Note: E: excellent, G: good, B: bad

The following points have been found from the above results:

(1) Since the HFC type refrigerant does not contain chlorine atoms, itis inferior to CFC type and HCFC type refrigerants in the lubricity of asliding portion.

(2) When the ratio of an alkyl group having 1 to 2 carbon atoms to analkyl group having 3 to 4 carbon atoms in the structure of the polyvinylether oil is made a predetermined ratio in accordance with the type ofthe above HFC type refrigerant and a predetermined vane material isselected in accordance with the ratio, the polyvinyl ether oil does notseparate when the separation temperature ranges from a high temperatureside to a low temperature side, that is, from 35 to 10° C. Thereby, therefrigerator can exhibit a predetermined refrigerating capacity.

Stated specifically, the relationship between the structure of thepolyvinyl ether oil and the separation temperature is shown in Table 5below.

                  TABLE 5    ______________________________________    The Relationship Between The Structure Of The Polyvinyl Ether    Oil And The Separation Temperature    high-temperature side/low-temperature side (unit: ° C.)    Structure    of R4    (C1˜C2/           Type of Refrigerant    C3˜C4)           Oil     R134a     R407C   R410A  R404A    ______________________________________    80˜100/           Type D  50 or more/                             50 or more/                                     50 or  44/-50 or    0˜20%    -50 or less                             -50 or less                                     more/  less    80˜100/           Type C  50 or more/                             50 or more/                                     50 or  37/-50 or    0˜20%    -50 or less                             -44     more/-23                                            less    60˜100/           Type B  50 or more/                             50 or more/    0˜40%    -20       -15    40˜100/           Type A  50 or more/                             50 or more/    0˜60%    10        -19    ______________________________________     REMARKS: The mark --" means that the separation occurs at entire     temperature range.

The same function and effect are expected from the following vanematerials as other examples.

For example,

(1) composite material comprising aluminum and carbon and having thefollowing composition

composition: C: 55, Al: 36, Si: 6, others (such as Mg): 3 (in wt %)

(2) fiber reinforced aluminum alloy having the following composition

composition: C: 55, Al: 36, Si: 6 (in wt %)

(3) ceramic such as zirconia (ceramic)

As described above, according to the present invention, thermal crackingcaused by frictional heat generated by sliding members and thegeneration of sludge can be suppressed by a combination of a specificHFC type refrigerant, a polyvinyl ether type oil having a specificstructure and a specific sliding material, and there is no carboxylicacid generated by hydrolysis when a conventional polyol ester type oilis used. As a result, a high-performance rotary compressor and coolingapparatus can be provided without the need for complicated processcontrol.

While the presently preferred embodiments of the present invention havebeen shown and described, it will be understood that the presentinvention is not limited thereto, and that various changes andmodifications may be made by those skilled in the art without departingfrom the scope of the invention as set forth in the appended claims.

What is claimed is:
 1. A refrigerant compressor comprising ahermetically sealed container and a compressor unit installed in thehermetically sealed container, wherein an HFC type refrigerant or amixture thereof and a refrigerator oil having compatibility with therefrigerant are charged into the hermetically sealed container, and therefrigerator oil essentially comprises a polyvinyl ether type compoundhaving structural units represented by the following general formula(1): ##STR8## wherein n is an integral number in the range of 1 or more,R1 to R3 are each a hydrogen atom or a hydrocarbon group having 1 to 8carbon atoms and may be the same or different, R4 is an alkyl grouphaving 1 to 4 carbon atoms, and units in which R4 is an alkyl grouphaving 1 to 2 carbon atoms are 40 to 100% and units in which R4 is analkyl group having 3 to 4 carbon atoms are 0 to 60%.
 2. The refrigerantcompressor of claim 1, wherein the refrigerant is selected from thegroup consisting of 1,1,1,2-tetrafluoroethane (R134a), an azeotropicmixed refrigerant consisting of 50 wt % of difluoromethane (R32) and 50wt % of pentafluoroethane (R125), and a pseudo-azeotropic mixedrefrigerant consisting of 44 wt % of pentafluoroethane (R125), 52 wt %of trifluoroethane (143a) and 4 wt % of 1,1,1,2-tetrafluoroethane(R134a).
 3. The refrigerant compressor of claim 1, wherein therefrigerator oil comprises 0.01 to 1.0 wt % of a phenolic antioxidant asan essential component and 0.01 to 2 wt % of an epoxy type orcarbodiimide type compound.
 4. The refrigerant compressor of claim 1,wherein the refrigerator oil comprises 0.1 to 2 wt % of a phosphoricester type compound.
 5. The refrigerant compressor of claim 1, whereinsaid compressor unit comprises a vane made from an iron type material ora carbon composite material infiltrated with aluminum and a roller madefrom an iron type material.
 6. The refrigerant compressor of claim 1,wherein said compressor unit comprises a vane made from an iron typematerial such as high speed tool steel or an SUS type material subjectedto a single or composite surface treatment by ion nitridation,nitrosulphurization or CrN.
 7. A refrigerant compressor comprising ahermetically sealed container and a compressor unit installed in thehermetically sealed container, wherein an HFC type refrigerant or amixture thereof and a refrigerator oil having compatibility with therefrigerant are charged into the hermetically sealed container, and therefrigerator oil essentially comprises a polyvinyl ether type compoundhaving structural units represented by the following general formula(1): ##STR9## wherein n is an integral number in the range of 1 or more,R1 to R3 are each a hydrogen atom or a hydrocarbon group having 1 to 8carbon atoms and may be the same or different, R4 is an alkyl grouphaving 1 to 4 carbon atoms, and units in which R4 is an alkyl grouphaving 1 to 2 carbon atoms are 80 to 100% and units in which R4 is analkyl group having 3 to 4 carbon atoms are 0 to 20%.
 8. The refrigerantcompressor of claim 7, wherein the refrigerant comprises at least twocompositions selected from the group of fluorinated hydrocarbonsrepresented by the following general formula (2):

    C.sub.l H.sub.m F.sub.n                                    ( 2)

(wherein when l=1, m=1˜2, n=2˜3 and m+n=4, when l=2, m=1˜4, n=2˜5 andm+n=6, and when l=3, m=1˜3, n=5˜7 and m+n=8).
 9. The refrigerantcompressor of claim 7, wherein the refrigerant is selected from thegroup consisting of an azeotropic mixed refrigerant consisting of 50 wt% of difluoromethane (R32) and 50 wt % of pentafluoroethane (R125), anda pseudo-azeotropic mixed refrigerant consisting of 44 wt % ofpentafluoroethane (R125), 52 wt % of trifluoroethane (R143a) and 4 wt %of 1,1,1,2-tetrafluoroethane (R134a).
 10. The refrigerant compressor ofclaim 7, wherein the refrigerator oil comprises 0.01 to 1.0 wt % of aphenolic antioxidant as an essential component and 0.01 to 2 wt % of anepoxy type or carbodiimide type compound.
 11. The refrigerant compressorof claim 7, wherein the refrigerator oil comprises 0.1 to 2 wt % of aphosphoric ester type compound.
 12. The refrigerant compressor of claim7, wherein the compressor unit comprises a vane made from an iron typematerial or a carbon composite material infiltrated with aluminum and aroller made from an iron type material.
 13. The refrigerant compressorof claim 7, wherein the compressor unit comprises a vane made from aniron type material such as high speed tool steel or an SUS type materialsubjected to a single or composite surface treatment by ion nitridation,nitrosulphurization or CrN.
 14. A refrigerant compressor comprising ahermetically sealed container and a compressor unit installed in thehermetically sealed container, wherein an HFC type refrigerant or amixture thereof and a refrigerator oil having compatibility with therefrigerant are charged into the hermetically sealed container, and therefrigerator oil essentially comprises a polyvinyl ether type compoundhaving structural units represented by the following general formula(1): ##STR10## wherein n is an integral number in the range of 1 ormore, R1 to R3 are each a hydrogen atom or a hydrocarbon group having 1to 8 carbon atoms and may be the same or different, R4 is an alkyl grouphaving 1 to 4 carbon atoms, and units in which R4 is an alkyl grouphaving 1 to 2 carbon atoms are 60 to 100% and units in which R4 is analkyl group having 3 to 4 carbon atoms are 0 to 40%.
 15. The refrigerantcompressor of claim 14, wherein the refrigerant comprises at least twocompositions selected from the group of fluorinated hydrocarbonsrepresented by the following general formula (2):

    C.sub.l H.sub.m F.sub.n                                    ( 2)

(wherein when l=1, m=1˜2, n=2˜3 and m+n=4, when l=2, m=1˜4, n=2˜5 andm+n=6, and when l=3, m=1˜3, n=5˜7 and m+n=8).
 16. The refrigerantcompressor of claim 14, wherein the refrigerant is a pseudo-azeotropicmixed refrigerant consisting of 23 wt % of difluoromethane (R32), 25 wt% of pentafluoroethane (R125) and 52 wt % of 1,1,1, 2-tetrafluoroethane(R134a).
 17. The refrigerant compressor of claim 14, wherein therefrigerator oil comprises 0.01 to 1.0 wt % of a phenolic antioxidant asan essential component and 0.01 to 2 wt % of an epoxy type orcarbodiimide type compound.
 18. The refrigerant compressor of claim 14,wherein the refrigerator oil comprises 0.1 to 2 wt % of a phosphoricester type compound.
 19. The refrigerant compressor of claim 14, whereinthe compressor unit comprises a vane made from an iron type material ora carbon composite material infiltrated with aluminum and a roller madefrom an iron type material.
 20. The refrigerant compressor of claim 14,wherein the compressor unit comprises a vane made from an iron typematerial such as high speed tool steel or an SUS type material subjectedto a single or composite surface treatment by ion nitridation,nitrosulphurization or CrN.